Yes, the dually axle is higher rated. I don't think it is safe to assume all 11. 5's have the same tube diameter, wall thickness, spindles, wheel/hub bearings, and reinforcing ribbing on the center section.
No need to assume. The axles are indeed the same. Per AAM the axle is rated for 10,912lbs in SRW or DRW. The axle diameter is the same on Dodge's, but smaller on GM's, and has no bearing on the rating. The wall thickness is adjusted to maintain the weight rating. The outer bearings on a DRW are larger to deal with the added mass of 2 tires, but it does not effect the rating.
The center section did change mid 2006, but that is a tooling thing and the older vs newer have zero difference in ratings. It was AAM's way of decreasing costs. The GM and Dodge had difference center sections up until mid 2006, now they are the same.
AFIK the '13+ DRW Max Tow gets a 11. 8" axle, but the remainder of the trucks still use the AAM 11. 5" axle. Can anyone clarify if only the Max Tow gets the 11. 8", or is it any 3500? Really a point of clarity, since the AAM 11. 5" can handle all the weight a SRW can throw at it.
There are at least 3 different RAWR for the same AAM 11. 5" axle in a Ram, 6,010, 6,200, and 9,350. They are all under the AAM rating.
Furthermore the frame is the same for 03-12 2500's and 3500's, regardless of engine and SRW/DRW configuration. This frame is also used on the '13 2500. It carries more GVWR's than I want to list, the highest being 12,300.
The 3/1 leaf pack used on DRW's 03-09, and all 3500's 11-12 is 7% stiffer than the 4/1 leaf pack used on the 2500's, 03-13, and 3500 SRW's 03-09. So you are a little softer than the truck equipped with a 7,000 lb RAWR, but it's not a large number. Airbags are the easiest way to increase suspension handling.
The wheel rating is unknown, and I have searched for hours and cannot find one. But they are heavy, solid, aluminum wheels an I have no doubt they handle more than the OEM 3195/tire.
So the bottom line is that you will be above the door sticker for RAWR, but I have yet to see where that is a legal issue. Tires are the issue, and 3,750 lb/tire is where you would have to stop. You are not putting any more stress on the configuration than anything that came from the factory with a different sticker, and the axle is the least of your concerns.
The only reason I can see they went to a 11. 8" ring gear was the added torque of the new 850 ft/lb motor. The AAM 11. 5" already required a lot of torque management on the 610 ft/lb motor, and wasn't updated over the years as the 6. 7 grew to 800 ft/lbs.
When my current tires wear out I will most likely be going to 19. 5" wheels and tires with a 4500 lb rating, and I wouldn't be the least bit worried about 9,000lbs on the rear axle of my SRW truck. As far as the truck is concerned it doesn't care if I have a SRW or DRW the ratings are all out there.
AFIK there are no OEM sway-bars on any 3rd or 4th gen on the rear of the truck.
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